Date of Award

Winter 1995

Project Type


Program or Major


Degree Name

Doctor of Philosophy

First Advisor

Frank G Rodgers


Listeria monocytogenes is the facultative intracellular pathogen responsible for causing the foodborne illness known as listeriosis. Disease occurs following invasion of cells of the intestinal tract by the organism following consumption of contaminated foods. In this study, a mechanism of opsonin-independent attachment of L. monocytogenes to host cells was identified. A clinical isolate of L. monocytogenes, together with murine-derived primary peritoneal macrophages were used to study this adherence phenomenon.

Transmission and scanning electron microscopy were used to visualize the attachment and uptake of L. monocytogenes by murine macrophages, while organism enumeration by viable bacterial cell colony counts was used as a measure of intracellular replication in host cells. L. monocytogenes was shown to adhere to host cells in the absence of complement and a complete infectious cycle for the organism was found. These data confirmed previously identified stages of host cell infection by L. monocytogenes in other cell types, including adherence, uptake, phagosomal escape, and intracellular replication.

The nature of the L. monocytogenes bacterial "adhesin" and the host cell "receptor" in binding studies was investigated. The results from competitive binding studies indicated the involvement of N-acetyl neuraminic acid, a member of the sialic acid group, in the binding of L. monocytogenes to murine peritoneal macrophages. Identification of the host cell receptor was not possible, as most treatments were ineffective at preventing organism binding.

Monoclonal antibodies directed against complement receptor 3 were used in blocking studies and these indicated that CR3 is not involved in the recognition of L. monocytogenes by nonlistericidal, thioglycollate-elicited macrophages. These results indicated the importance of opsonin-independent binding mechanisms for L. monocytogenes and shed new light on our understanding of the infectious processes of this pathogen.